Circuit breaker locking device



CIRCUIT BREAKER LOCKING DEVICE Filed April 14, 1942 s Sheets-Sheet 1 Dec. 10, 1946.

CIRCUIT BREA KER LOCKING DEVICE W. M. SCOTT, JR

Filed April 14, 1942 6 Sheets-Sheet 2 INVENTOR.

BY Q i b 10, 1946. w SCOTT, JR 2,412,294

CIRCUIT BREAKER LOCKING DEVICE Filed April 14, 1942 6 Sheets-Sheet INVENTOR. Mm? M 5' mad at BY 2 z Disc. 10, 1946. sco'r'r, J 2,412,294

CIRCUIT BREAKER LOCKING DEVICE Filed April 14, 1942 6 Sheets-Sheet 4 IINVENTOR.

Dec. 10, 1946. w. M. SCOTT, JR 2,412,294

CIRCUIT BREAKER LOCKING DEVICE Filed April 14, 1942 6 Sheets-Sheet 5 INVENTOR. 210m M 520:: J

ZJW

Dec. 10, 1946. w. M. SCOTT, JR 2,412,294

CIRCUIT BREAKER LOCKING DEVICE Filed April 14, 1942 6 Sheets-Sheet 6 Patented Dec. 10, 1943 CIRCUIT BREAKER LOCKING DEVICE William M. Scott, Jr., Bryn Mawr, Pa., assignmto I. '1. E. Circuit Breaker Company, Philadelphia, Pa, a corporation of Pennsylvania Application April 14, 1942, Serial N 0. 438,871

16 Claims. 1

My invention relates to circuit breakers and particularly to operating mechanism therefor and apparatus for locking the operating mechanism to maintain the circuit breaker in closed position.

Primarily, my invention is designed for use in connection with circuit breakers which are to withstand severe shocks without bein tripped.

Where circuit breakers are utilized to control electrical apparatus in naval craft of various types, it may at times become desirable to ensure that the circuit breaker will, under no circumstances, be tripped open irrespective of the shock or jar which it may receive; and indeed irrespective of the nature of the overload to which the circuit it protects is subjected.

Where naval craft are subjected to the shock of gun fire (recoil or impact) such shocks necessarily occur on occasions when it is more desirable to maintain the operation of apparatus rather than to protect the apparatus against injury from overload. In such cases the tripping open of a circuit breaker in order to protect specific apparatus may actually result in disabling of the vessel.

In other Words, there are conditions which may be encountered by naval craft where it is desirable to maintain apparatus in operation to the last possible moment irrespective of injur to the apparatus itself. When such conditions occur, it becomes necessary to lock the circuit breaker closed to prevent its opening under any shock or impact of any foreseeable nature.

An object of my invention, therefore, is to provide a lock-in device for a circuit breaker which will maintain the circuit breaker contacts in closed position irrespective of the physical shock or electrical overload to which it may be subjected.

Another object of m invention is to provide in connection with the circuit breaker operating mechanism a lock-in device which may be easily manipulated by even an unskilled operator.

A further object of my invention is to provide a lock-in device for a circuit breaker for the purposes above set forth wherein the lock-in device is operable in connection with the closing and tripping mechanism of the circuit breaker to render the tripping mechanism inoperative and to lock the closing mechanism in position where it supports the movable contact in engagement with the stationary contact.

A further object of my invention is the provision of a lock-in device for a circuit breaker which will render the tripping latch inefiective.

An additional object of my invention is the provision of a lock-in mechanism which will positively engage a closing toggle of a circuit breaker to prevent collapse thereof under any circumstances.

Still another and important object of my invention is the provision of a lock-in device which itself is shock-proof so that it may not itself be jarred out of position.

These and many other objects of my invention will become apparent in the following description and drawings in which:

Figure l is a side view partly in cross-section of a circuit breaker of the type in connection with which my lock-in device may be used.

Figure 2 is a side view with the side cover broken away of the operating mechanism for the circuit breaker of Figure 1 showing the position of the operating mechanism when the circuit breaker is open.

Figure 3 is a view corresponding to that of Figure 2, showing the position of the operating mechanism when the circuit breaker is closed.

Figure 4 is a cross-sectional View taken on line 44 of Figure 2 looking in the direction of the arrows.

Figure 5 is a cross-sectional view taken on line 5-5 of Figure 3 looking in the direction of the arrows.

Figures 6, 7, 8 and 9- are diagrammatic views showing various steps in the operation of the members of Figures 2 and 3; Figure 6 showing an open condition of the circuit breaker; Figure 7 showing the closed condition of the circuit breaker; Figure 8 showing the circuit breaker locked in position by the lock-in device of the present invention; and Figure 9 showing a position which the circuit breaker operating mechanism maintains during tripping thereof and during the movement of the parts from the Figure 7 position to the Figure 6 position.

Figure 10 is a view in perspective of the lock-in device of my invention showing the manner in which the same may be combined with portions of the operating mechanism of Figures 2 and 3.

Figure 11 is a view in perspective corresponding to that of Figure 10 but showing the movement of the lock-in device to effect a tripping of the circuit breaker.

Figure 12 is a view corresponding to that of Figure 10 showing, however, a movement of the lock-in device to prevent the closing of the circuit breaker.

Figure 13 is a top view of a portion of the elements of Figure 10.

Figure 14 is a top view of a portion of the elements of Figure 12.

Figure 15 is a front view and Figure 16 is a side vieW of the lock-in device elements corresponding to the position of Figure 10.

Figure 17 is a front view and Figure 18 is a side view of the lock-in device elements corresponding to the position of Figure 11.

Figure 19 is a front view and Figure 20 is a side view of the lock-in device elements corresponding to the position of Figure 12.

Figure 21 is a cross sectional View taken on line iii-2i of Figure 13.

Referring now to the figures, the operation of my circuit breaker lock-in mechanism may best be understood from a preliminary description of a typical circuit breaker in connection with which the same may operate.

In Figure 1 I have shown a circuit breaker of the type more specifically described in application Serial No. 339,682 of Pokorny, and application Serial No. 339,687 of Scott, both filed June 10, 1940, which became, respectively, Patent No. 2,390,735, on December 11, 1945, and Patent No. 2,3e8,228, on May 9, 1944.

This circuit breaker may consist of one, two, three or more poles operable by a single operating mechanism.

Each of the poles 2c is mounted on the face of an ebony, asbestos or slate panel 23 which forms the mounting plate of the entire circuit breaker arrangement.

The main bracket or housing 2 which supports the operating members is secured to the panel 23 by means of screws the heads of which are recessed in the openings 26 in the back of the panel and which pass through perforations 27 in the panel to engage the main bracket.

fhe bracket 24% consists of flanged side plates 23 which extend on each side of a horizontal shelf 3%? to which they are welded, or otherwise secured.

The operating mechanism is contained in housing 31 and is bolted to the lower side of the shelf 36 by bolts 33 passing through flanges in the housmg.

Link as. connects the operating mechanism in housing t! to the lever 35 which is secured to the contact carrying shaft and rotatable therewith. The contact carrying shaft :25 is a steel member of square cross-section covered with suitable phenolic insulation and is rotatably mounted between the side plates 28 of the main bracket 2 The main stationary contacts 36 are secured to a back connection stud d2 which is mounted on the panel above the bracket 24 and support the inner ends of the arc chutes in the manner hereinafter described. A bridge 37 of insulating material secured to the outer end of the bracket 24 supports the outer end of the arc chutes.

The path of the current when the contacts are closed is through the connection stud 42, the stationary contact 36, the stationary tip it), the movable contact tip M mounted on the contact lever of) which carries the flexible connection 33, th opposite end of which is connected to the lower terminal 64 which, through the over current trip coil Hi! is connected to the lower back connection stud Ill.

The contact lever 69 is mounted on the contact carrying arm 58 which, in turn, is secured to and rotatable with the contact carrying shaft Q5.

The particular arrangement of the contact lever and the resilient mounting thereof on the con-- 4 tact carrying arm is more fully described in the aforementioned applications of Pokorny and Scott, as well as in Scott application Serial No. 339,689, filed June 10, 19 10, which became Patent No. 2,375,328 on May 8, 1945.

The movable arcing contacts El are mounted in the upper part of the contact carrying arm it and are supported by arcing contact levers E5 so that during the opening movement of the circuit breaker they disengage the stationary arcing contact 12! after the movable contacts have disengaged.

The particular arrangement and mounting of the arcing contacts to produce this result is also more specifically described in the applications above mentioned.

A flexible lead 93 is secured to the lower end of the arcing contact lever and at its opposite end is secured to the terminal post M.

The stationary arcing horn 23b is mounted in the arc chute tee and connected by a flexible lead 198 to the lower terminal it.

Since the leads 43, 93 and 190 are connected to the lower terminal block M, the blowout magnet I22, as hereinafter described, will thus be in series first with the main contacts, then with the arcing contacts, and finally with the arcing horns.

When the main contacts are disengaged, current flows to the arcing contacts through the blow-out coil as follows: From the upper back connection stud 52, current flows into the lower terminal block of the blow-out magnet coil I22, around the coil to its upper terminal plate I29 and thence to the stationary arcing horn I23 which is secured thereto. The current then flows to the stationary arcing contact [2L thence to the movable arcing contact 81, then through the arcing contact lever 75, the flexible lead the terminal block it, the coil IE9, and the connection stud ill in the manner hereinbefore described.

The upper part 138 of the arcing horn i213 is extended along the panel and forms a hook for anchoring the back end of the arc chute. The front of the arc chute use is locked in place by a screw 62 passing through a lug 53 in the arcing horn I68 which is mounted in the chute I55 and through a conductive plate It: secured to the insulating bridge 37.

The blow-out coil l 22 is so arranged as to drive the arc upwardly into the arc chute E58.

The specific form and operation of the blow-out coil is set forth in the applications above described and also in application Serial No. 339,688 of Scott, filed June 10, 1940, which became Patent No. 2,311,701 on February 23, 1943.

The specific internal structure of the arc chute which serves to extinguish the arc is described and set forth in application Serial No. 384,245 of Graves, filed March 20, 1941, which became Patent No. 2,338,715 on January 11, 1944. The Various members of the circuit breaker are described in these general terms since the specific portions thereof may be varied without departing from my invention.

My invention relates to members operable in connection with the closing and tripping mechanism of the circuit breaker and may be adapted to circuit breakers having contact'assemblies, arc chutes, blow-outs, and other elements which are completely different in form and operation from the clrcuitbreaker herein described. The present circuit breaker is described as a type in connection with which my invention may operate.

The contact carrying shaft 45 is biased by a spring (not shown) to rotate in counterclockwise direction with respect to Figure l.

The operating m chanism hereinafter described serves to rotate the shaft i5 and its contact carrying arm 48 in clockwise direction against the bias of its opening spring and to maintain the contacts in closed condition against this bias.

When the circuit breaker is tripped, members which maintain the shaft 55 in closed position are released and it is able then to respond to the opening bias of its spring in order to rotate the movable contacts counterclockwise to open circuit position.

Any circuit breaker which has a movable con tact which may be moved to engagement with a stationary contact and which is held in engagement against the bias of an opening spring may be utilized in connection with the operating mechanism and lock-in device hereinafter described.

The operating members contained in housing 3| are shown more specifically in Figures 2 and The housing 3! is a steel box closed on the front, bottom and sides and is provided with flanges 32 at the upper edges of the sides so that it may be secured by bolts 33 to the shelf 38 of the housing racket assembly. The side walls of the housing are pierced for the main stationary pins of the mechanism and the metal around the holes is extruded inwardly and reamed to obtain proper bearing for the pins.

The operating mechanism comprises a plurality of toggles so arranged that the knee pins of each may be supported when the contacts are closed; but wherein the supports may be removed, permitting the contacts to open when the tripping operation is eifected.

One of the toggles comprises an op rating link 200 preferably and for structural reasons, forme from a pai of side plates connected by a tie plate 203. Link 200 is rotatable on the fixed pivot 204 which is carried in perforations of the side walls of the casing.

The link 200 also carries on its opposite end rotatably mounted between its side plates the knee pin 205.

Link 200 which also is formed from a pair of side plates having a rigidifying tie plate 209 therebetween is rotatably mounted at one end on the knee pin 205 and carries at its opposite end a pin 2 i 0.1

A lug 2i i is rotatably mounted on pin 280 and a tension spring 2l2 is secured thereto. The opposite end of spring 252 is secured to a lug 2E8 which is rotatably mounted on a pin 2M carried by the upstanding lug 2 i 5 of one of the side plates of the link 200.

The effect of tension spring 2l2 is to collapse the toggle 200-200 to the position shown in Figure 2.

A third link 2i6 which may be formed from a pair of independent side plates is rotatably mounted at one end on the pin 2i0 and at the opposite end is connected to the pin 22? which is carried by the latch lever 2 i 8.

The latch lever also comprises a pair of side plates having a rigidifying tie plate 22l therebetween. One end of the latch lever 2l3 is rotatably mounted on the fixed pin 222. Pin 2H3 also rotatably supports one end of the connecting link 34 which extends between the operating mechanism and the actuating arm of the contact carrying shaft. This link is a single wide member of phenolic insulation.

An abutment 225 is also rotatably mounted on the stationary pin 222 and comprises a V-shaped member having a center portion 220 which is pivotally mounted on the pin 222, an abutting por tion 22'. adapted to engage a roller on the in 205 a release portion 223 shown entirely in dotted lines behind the latch lever 2 i S in Figures 2 and 3.

The upper edge of release portion 223 is in engagement with the under side of tie plate 22i of the latch lever 2IS so that any downward movement of the latch lever will result in a clock wise rotation of the abutment 225 and thus will result in moving the abutting portion 227 thereof out of engagement with the roller on pin 205.

A spring 240 is so arranged as to yieldingly support the abutment member 225 so that the abutment 22'! may always be in position to engage the roller 205.

Pressure of the release portion 22;: against plate 22| of the latch lever limits the effect of the spring 220 and serves positively to position latching portion 22? in predetermined position.

When link 200 is raised and the knee pin 205 of the toggle formed by the links 209-406 is, therefore, raised, then since the link 250 (by reason of its attachment between pins 210 and 211) prevents pin 2 II] from approaching closer to the pin 214, the only direction in which link 206 may rotate is such that pin 210 moves clockwise with respect to pin 205.

Raising of link 200 results in extension of the spring 2l2 (the members assuming the position shown in Figures 3 and 7), and in an increase of force tending to draw the pins 2l0 and 2M together, thus creating a tendency to collapse toggle 206-400 (since this toggle does not move through center).

When, therefore, the supporting means herein described has been removed from the toggle, it will immediately collapse owing to the tendency of the spring 2l2 to draw pins 216 and 244 together.

When the members are moved from the position of Figures 2 and 6 to the closed position of Figures 3 and '7, pin 2|! remains stationary since it is mounted on the latch lever 218, one end of which is fixed by its mounting on pin 222 and the other end of which is fixed by engagement of the latching tip 230 thereof with the notch 23E of the primary latch 232.

Therefore, during the closing operation, the center of rotation of link 2IB is fixed and for this reason also pin 2|0 is to some extent at least supported by link ZIB. This partial support results in downward pressure upon a latch lever H8 in the closed position of Figures 3 and 7 thus resulting in pressure of the latch lever tip 230 upon the base 233 of the notch 23!.

As the operating link 200 is raised, the roller on pin 205 comes in contact with the surface 234 of the abutment 225 and moves the same in a clockwise direction so that the knee pin 205 may rise.

After the pin 205 has passed the area 234, then the spring 240 of the abutment pushes the abutment 225 in a counterclockwise direction so that member 228 of the abutment abuts against tieplate 22! of the latch lever H0 and so that the abutting portion 221 is swung beneath the roller on knee pin 205 to support the same against the tendency of spring 2 12 to collapse the toggle.

The abutment 227 may again be rotated clockwise out of engagement with the roller and pin 205 by any force which may depress the latch lever 218.

The means by which this is accomplished includes the primary latch 232 and the secondary milled latch 256.

For this purpose also it should be noted that knee pin 2th of the toggle formed by links 34 and 2H5 does not pass through center, when the closed position is reached so that this toggle may also be collapsed. The collapsing pressure on this toggle is that which is exerted by the contact opening spring to cause a counterclockwise rotation of shaft is. This counterclockwise rotation creates a downward pressure on link as which, through pin 2H! and link 2E6, is transmitted to the pin 21'] carried by latch lever 2l8.

All of the knee pins are supported in closed position. Knee pin 255 is supported by the abutment 225; knee pin tie is supported in part by the stabilized position of knee pin 2% and in part by the stabilized position of pin 2 i I.

When support is removed from the latch lever 218 and it is allowed to drop under the substantially vertical downward pressure exerted thereon through links 3 and 216 (when in the closed circuit position of Figtues 3 and 7), then as the tip 236 of lever 253 drops, the tie plate which is in contact with portion 228 of abutment 225 rotates the same to move it out of supporting position for the pin 2%.

Toggle 2tlii-2t5 then collapses under the influence of spring 212 causing thetog'gle 34 2!?! to collapse thus resetting the mechar'iism.

The circuit breaker opening operation does not, however, depend on the collapse of toggle 2tt2ili5.

When the support is removed from the latch lever 2l8, it may immediately drop under the influence of the downward pressure of links 34 and 2N; and thus momentarily assume the position shown in the diagrammatic showing of Figure 9.

The abutment 225 is thereby swung out so that it no longer supports pin 205, and toggle 2iit2ii6 may collapse, thus restoring the members to the position shown in Figure 6. V v

The purpose of spring 2l2, therefore is to reset the mechanism after a tripping operation has occurred.

The circuit breaker operating mechanism may be trip free. Thus, as seen in Figure 9, latch l'e've'r 2R8 may trip when released from its primary latch under the pressure of links 35 and-236, even though toggle Bile-2% is not collapsed. This may occur, for instance, when the operating link 2% is held in raised position either manually or otherwise. In this case, on release of the ma'nual pressure which holds the link 2% in raised position, the mechanism isagain moved to the position shown in Figure 6 where it is ready, once more, for a closing operation.

When the mechanism is permitted to move from the position of Figure 7 through the position of Figure 9 to the position of Figure 6 without being impeded by any manual closing pressure, then, when the contacts open, the pin 2H1 is first moved downwardly as shown in Figure 9.

Thereafter the pin is moved toward the left with respect to Figures 2, 3, 6, '7 and 9,

As this occurs, the link 2H exerts an upward pull on the latch lever 2l8, thus resulting in a rise once more of the latch lever and thus also permitting the abutment to swing back to its original position.

Thus the downward pressure of link 2% wing to the opening pressure of the opening "spring of the circuit breaker depresses the latch lever when the support therefor is removed. Thereafter, the toggles are reset by the tension spring 212, the upward or counterclockwise force exerted by the lever 2ft serves also to reset the latch lever The primary latch 232 and the secondary milled latch 250 are designed so that in addition to readily tripping the circuit breaker, they may automatically be reset by such upward movement of the latching tip 230 of the latch lever 2 H5.

The primary latch comprises a curved link 232 which is pivotally mounted on the stationary pin 260.

Member 232 has a front cam surface 26L the notch 2S5 hereinbefore described, the latch lever abutment 233, and the resetting toe 262. This primary latch is maintained in latching position by the inilled latch 2583 which normally prevents counterclockwise rotation of the latch 232.

When restraint against counterclockwise rotation of the latch 232 is removed, then pressure of the tip 23% of the latch lever 253011 the abutportion 233 of the notch '23! causes latch to rotate about its pin thus releasing the latch lever 253 and allowing the pressure thereon to cause it to drop.

The forcing down of latch lever 2 i8 also forces abutment 2255 out of position and permits the main contacts to open in response to the contin'uation of the opening spring.

The position as the dropping motion or" the latch lever completed is shown in the schematic view of Figure 9. This position occupies but a brief moment during the tripping operation and. is but one stage of a continuous movement.

As link 2E6 swings about its pivot 2H by reason of the drawing together of pins 2m and 214, then the previous downward pressure exerted by link 2 it becomes a pull (owing to tension spring 2l2).

This results in counterclockwise rotation of the latch lever and a raising of the latching tip Zti thereof.

As the latch lever is pulled up, the pressure of its tip against the cam surface 255 prevents the resetting of the primary latch 232 until tip 238 strikes the projecting toe 262. The pressure of the upward movement of the latch tip 2% bei the toe 262 now rotates the primary latch 232 clockwise toward the position thereof shown in Figures 2 and 6 so that the latch tip enters the notch 223i and lies between toe 262 and abutment 233 in preparation for any subsequent closing or tripping operation which may be required.

An abutment 362A on the bottom wall of the housing engages the extension 302 of the primary latch 232 to limit its rotation when the toe thereoi is struck by the latch lever.

The milled latch 250 restrains the primary latch 232 against any rotational movement in response to downward pressure on the latch lever 2E8.

The milled latch 250 cannot return to its original restraining position, however, until the primary latch has been engaged, since the movement of the latch tip 2353 against the cam surface 25! maintains the primary latch in its released position until the tip 230 is engaged in the notch 23L The milled latch 25% is a shaft 3% having a portion 25c milled out, the milling being of sufficient depth to permit the base or latch engaging portion 39f of the primary latch 2 32 to pass therethro'ugh when shaft 300 is rotated counterclockwise.

The extension 392 on the bottom of the primary latch lies adjacent the base or latching tip 3!!! thereof to limit the movement of the base into the milled latch 250. The milled latch and its shaft sea is normally retained and biased towards the latching position by spring 305 which exerts a clockwise force thereon.

Shaft 39f! rotatably mounted in suitable hearings and carries tripping arms 304 preferably of insulating material keyed thereto or molded thereon. The spring 355 which maintains the milled latch suitable latching position is connected to a stud 3536 on the shaft 550'.

The opposite end of this spring is passed through and thereby attached to an eye in the lug 303 in the side wall of the housing.

Arm 3% (see Figure may also be mounted on the shaft 359 carrying the milled latch and abuts against the manual tripping arm 3!!! which thus also limits the rotational movement of the shaft 329 in response to spring 355.

Milled latch 256 is of the variety generally known as dead center latch wherein the force exerted by the latching tip 321 of the primary latch 232 does not tend to induce any movement of the latch 253 but is substantially directed toward the center thereof inducing a condition of stability. I

When the shaft 300 is rotated counterclockwise then it need not overcome any substantial force tending to impede its rotation since the only resistance to such rotation is the spring 355 which is merely suflicient to maintain the latch in stationary position and the slight friction between the latching tip of the primary latch and the side of a shaft 300.

Automatic tripping may be effected by the raising of the armature 52| of tripping coil III] to abut against the tripping arm 3% and rotate the shaft 3% counterclockwise.

Manual tripping may be effected by a rotation of the tripping arm 3H3 (Figure 10) clockwise around its pin 3i l to engage the tripping arm 399. The tripping arm 3H3 may be operated by the lock-in device herein described.

The operating lever 25!] may be moved to circuit closing position either manually or magnetically.

Electrical operation is obtained by energization of closing solenoid coil to raise the armature 332 which engages the knee pin 255 and thus raises operating link 20%].

Manual closing is obtained by the rotation of handle szc. Handle 320 is keyed to the squared shaft see which in turn is inserted in the squared hollow portion of the cylindrical casting 352 and held therein by a set screw.

Square shaft 350 is, of course, of any suitable length depending on whether or not a cover or casing is to be used for the circuit breaker.

The cylindrical casting 352 carries thereon a helical cam 353 which engages a roller 355 on a downwardly depending lug 354 of the operating arm 2%. On manual rotation of the handle 326, clockwise with respect to Figure 4, the helical cam 353 will raise roller thus raising the link 2552 and thus closing the circuit breaker. The handle may then. automatically return to neutral position.

The means provided for causing this return consists of an arm mounted on the shaft 350, the said arm carrying a roller 4!. Roller 10 Mil registers with a notch 403 in the lever 424 when the handle 32% is in neutral position.

Lever M34 is pivoted on the stud Hi5 and is maintained in raised position by the spring 586 which engages 2. lug on the lever 35% and the other end of which is engaged by a lug 363 in the bottom of the housing,

The position of the members of Figure 5 shows the position of these elements when the circuit breaker handle is rotated to close the same. This operation results in rotation of shaft 353 clockwise with respect to Figure 5, thus causing the roller set to ride out of notch 4633 and on to'the upper surface of the lever ills. This rotates lever ass .bout the pin 6515 thus extending the spring 588.

When manual closing pressure is removed from the handle 326 then the tension on spring 455 causes the lever to rotate counterclockwise, thus causing roller as: to ride down the lever and into notch This results in a consequent rotation of arm and of shaft 359, thus resetting the mechanism.

In th foregoing I have set forth in schematic form an operation of the circuit breaker closing and tripping apparatus. This apparatus is more specifically described in the applications above set forth.

The present invention does not concern itself directly with the operating mechanism herein described but with a lock-in device which is applicable thereto.

A full understanding, however, of the construction and operation of the operating mechanism of the circuit breaker is necessary to an understanding of the operation of the lock-in device.

The lock-in device herein described and the integration thereof with the operating mechanism may now be fully understood.

Essentially, the lock-in device is arranged to render the milled latch 259 ineffetcive and is further arranged so that the shaft Sflil is moved axially so that the milled portion 25!! thereof is moved out of engagement with the latching tip 334 of the primary latch 232. This provides an absolute means for preventing the rotation of the primary latch 23% clockwise with respect to Figures 3 and 7 since it'will then be in engagement only with a solid shaft.

Also, the lock-in device is so arranged that the operating link 2553 may be locked in raised position thus locking the pin 255 in raised position so that any force which may jar the abutment 225 out of position will not have the result of collapsing the mechanism.

That is, the operating mechanism, as is now understood. supports the circuit breaker contacts in closed position by reason of the fact that pin 265 is supported and by reason of the fact that the primary latch 232 is restrained from counterclockwise rotation. The lock-in device of my invention is designed to prevent counterclockwise rotation of the primary latch and is designed to support the pin 2B5, irrespective of what may happen to the abutment 225.

The lock-in device is shown in the ordinary unlocked position in Figure 10 and consists of a cylinder 5% having two shafts and 5&2 extending from opposite ends thereof.

The cylinder and shafts are preferably formed from a single steel casting. Each of the shafts 5e! and is eccentric with respect to the center of rotation of the cylinder 59%; that is, cylinder 500 rotates in appropriate bearings in a housll ing 5&3 which is secured at one side to the principal housing 3% of the operating mechanism.

In the view of Figure 10, each of the shafts 5M and 5%? is directly below the center of rotation of cylinder Silt. Shafts 5&5 and 55.2 are coaxial with each other so that whatever position shaft 5M may assume with respect to the mechanism, shaft will assum an exactly similar position.

The cylinder 5% is maintained in a position where it is normally forced toward the left (outwardly) by the compression spring 585, one end of the spring being secured at 5535 in an end wall of the housing 5%, the other end of the spring being secured beneath the head of a screw 56% which passes through the cylinder 50!).

The position of cylinder Elli! is fixed by the engagement of the left hand member are of the casting 5i 5 against the tripping arm sue, the

position of which is fixed by its being mounted on the pin 3| I. This position is also fixed by the screw 52H in the channel 522 as hereinafter described.

The casting 5M (hereinafter more specifically described) is secured to the right hand end of the shaft 592 and may be integral therewith or welded thereto.

The front end of shaft 5! is provided with a squared extension 5l3 over which a handle may be mounted. Rotation of the squared extension will result in the rotation of the shaft and in consequent rotation of the cylinder 5 5i! and also in rotation of shaft 562.

Since shaft 552 is eccentric with respect to the center of rotation of cylinder Mill. this o eration will result in rotation of the tripping arm 3H1.

Th pin 3!! which carrie tripping arm 35B is mounted directly beneath the center of rotation of the cylinder 5%. Accordingly, when the squared extension 513 is rotated counterclockwise with respect to Figure 10, thus rotating the cylinder 5B8 counterclockwise, then the rotation of the shaft 562 also counterclockwise will result in a clockwise rotation of the tripping arm SlO around the pin 3! l.

This is so since the eccentrically mounted shaft 562 passes between the tines 515 and 5I6 of the bifurcated extension ill of the tripping arm 3H3. Such clockwise rotation of the tripping arm 3H3 will cause the arm 3&9 mounted on the extension 569 of the shaft 3% to be rotated counterclockwise, thus rotating the shaft Silt counterclockwise and thus tripping the latch; that is. the abutting portion 3%! of the primary latch 232 is then brought opposite the milled portion 259 of the shaft 390 and permitted to enter therein and trip the circuit breaker.

Such an operation produces exactly the same rotation of shaft 396 as would the automatic tripping mechanism which would cause the arm 3% of shaft ass to rotate counterclockwise.

The compression spring 505 also serves as a spring which biases the cylinder Elli) toward the angular position shown in Figure 10. Accordingly, upon release of manual pressure from the handle on the squared extension EH3, the cylinder 5% will, after the tripping operation, return to the position shown in Figure and be in position for any further operation which may be required.

The tripping operation is shown in Figure '11. Here it is seen that the squared extension 553 has been rotated counterclockwise thus rotating the shaft 502 counterclockwise and rotating the tripping arm 3!!) clockwise to rotate the milled shaft 300 counterclockwise to cause the trip- 12 ping of the primary latch 232 in the manner previously described.

The normal position of the parts of Figure 1 are shown also in the front and side views of Figures 15 and 16.

The operation which effects the tripping of the latch is also shown in the front and side views of Figures 1-7 and 18, the position of the parts of which correspond exactly to the position of the parts of Figure 11.

Here it will be noted, particularly with to Figures 11 and 18, that a set screw 52E is provided in the base of the housing and engageable with a channel 522 in the cylinder 5%.

This channel consists of a circumferential portion 52d, a longitudinal portion 525 eXtending normal to the first circumferential portion, an additional circumferential portion 523 and an additional longitudinal portion 52?.

When the cylinder 5% is in the neutral position shown in Figure 10, the head of the set screw 52H is positioned in the channel 522' at the juncture between portions 52 and 525.

The circumferential portion 52 of the channel permits the counterclockwise rotation of the cylinder 55%] by a handle mounted on the squared extension 5ft so that a tripping operation may be effected. However, rotation of the cylinder 5% clockwise is resisted by the fact that such clockwise rotation brings the side of channel 525 against the head of the screw 52!.

Accordingly, it is normally impossible without any further movement to rotate cylinder 56% clockwise. However, the primary function of the apparatus shown in Figures 10 and 11 is to provide a lock-in for the circuit breaker which will prevent operation of the primary latch 232 and the milled latch 259.

This function is achieved by an axial movement of the cylinder toward the right with respect to Figure 10 so that the spring 5&5 is compressed when the handle mounted on the squared extension 5l3 is pushed inwardly with respect to the front of the circuit breaker mechanism (and toward the right with respect to Figure 10). The casting 5i i on the opposite end thereof likewise pushed toward the right.

The casting 5!! consists of two circular side plates are and 536 on opposite end of a small shaft 531. Th side plates hit, 536 and the shaft 53! are preferably welded together or may be integral and the entire casting is secured to the shaft 532 by welding the side plate Eiil on to the end of that shaft. However, the side plate Sill is welded to the shaft 5G2 so that a portion of the plate adjacent to the periphery thereof engages the shaft 5%.

The arrangement is such that the small shaft 535 between the side plates 5H) and 53% is coaxial with the cylinder 599 so that it has no eccentric rotation with respect thereto.

A bell crank lever 535 is mounted by a suitable vertical pin 536 in the housing so that it may rotate about the pin. The arm of the bell crank lever has a clevis 539 at the end thereof, the tines of which are engaged between the plates MB and 538 on either side of the shaft hill.

The opposite arm 548 of the bell crank lever also has a clevis 5M, the tines of which extend on either side of the shaft 519. which is extension of the milled shaft 368. This clevis is captured between the side plate 5&5 mounted on the shaft 5E9 and the end of the shaft 3%.

Accordingly, when the handle carrying extension 5l3 is pushed toward the right, thus pushing the cylinder toward the right against the compression of the spring, casting is also pushed toward the right.

The engagement of plate 510 with the clevis 539 causes a counterclockwise rotation of the bell crank lever 535. This, therefore, causes a corresponding movement of the opposite clevis 54! of the bell crank lever and thus causes the milled shaft 3.98 to slide toward the left. This is made possible by reason of the fact that the shafts M9 and 550, each constituting extensions of the milled shaft 3&0, are rotatably positioned in rather narrow bearings 560 and 55! (Figures 13 and 14) so that they may slide longitudinally with respect thereto.

When the milled shaft thus is now slid to the left (with respect to Figures 10, 12, 13, and 14) by this motion, the milled portion 253 of the shaft is slid beyond the latching tip 353:" of the latch lever of the primary latch 232. That is, as may readily be seen, especially in Figures 13 and 14, the milled portion 255 of the shaft Sill! is rather narrow in area and, in fact is just wide enough to permit the primary latch 232 to enter therein. When the shaft 30!! and the members carried by it are moved to the left, then the milled portion (250 of the shaft is moved away from engagement with the latching tip Bill of the primary latch 232. The primary latch 232 cannot, therefore, under any circumstances, enter into the milled portion and is fixed against rotation by its engagement with the unmilled portion of the shaft.

No tripping movement which is imparted to the shaft 3% could in any way cause the prilatch to enter the milled portion of the shaft. Furthermore, any tripping movement which may be imparted to the shaft 3% by an armature which strikes the arm 334 will, nevertheless, rotate the shaft 353 without eifecting an opening of the circuit breaker.

In this manner, many difliculties in the prior art are obviated, since the members which are engaged by the tripping armature may yield with respect thereto when the trip coil is energized.

Thus the arm of the milled latch will be engaged by the tripping armature (under fault conditions) and rotated thereby to rotate shaft 3% without, however, tripping the circuit breaker.

This is so, particularly since the shaft 360 may rotate in response to any tripping movement while when the lock-in is effective, the milled portion thereof is not brought into position to effect the opening of the circuit breaker.

When the cylinder 5% has been moved axially the manner herein described, it is necessary to lock the same so that it cannot be moved out of position by the compression spring 535 and so that it cannot be jarred out of position.

The lockin movement consists of a subsequent rotation of cylinder 5%. Thus, when the cylfinder is moved to the right with respect to Figure 18, the head of the set screw 52! may slide down the portion 525 of the channel 522.

At this time, when it reaches the end of this .tlon of the channel, then it is free to be moved along portion of the channel. Consequently, after the axial movement is effected, then the handle of the squared extension 5H3 is rotated clockwise to the position shown in Figure 12 and the sad of the set screw 52! passes down the portion 26 of the channel until it reaches the portion 521 thereof.

The portion 52'! of the channel is shorter than the portion 525 of the channel 522. The compression sprin may now, therefore, force the cylinder 5% back (to the left) so that the inner end of the portion 521 of the channel is engaged by the set screw. The compression spring now maintains a pressure at the end of channel 521 on the set screw 52L Since the portion 521 of the channel is just long enough to permit this locking action to take place by reason of the action of the compression spring and since it is not as long as the channel 525, then the position of the members which is obtained by this movement of the cylinder 5G0 axially is held as long as the cylinder is left in the position shown in Figure 12. Further, since spring 555 is also a torsion spring (exerting its force in a clockwise direction) it assists in holding cylinder 582 in the position of Figure 12.

In Figures 13 and 14, I have shown top views of this operation; Figure 13 corresponding to the position of Figure 10 and Figure 14 corresponding the position of Figure 12.

Here it will be seen that the shaft extensions 5H) and 55%! are slidable in the bearings 568 and 555 which are supported by the walls of the housing 3i The front and side views Figures 19 and 20 correspond to the position of the members in Figures l2 and 14.

This operation, while it results in rendering the tripping latches 255 and 232 absolutely inoperative, may, in certain circumstances, however, not be suticient to ensure the maintenance of the circuit breaker in closed position against any shocks or jars.

I provide, therefore, additional members on my lock-in and operating mechanism which will also serve to hold the operating link 2053 in raised position irrespective of any shocks or jars which may accidentally move the abutment 225 out of supportin position.

When the operating link 2% is thus held in raised position and when the milled shaft 398 is moved so that the milled portion 259 thereof cannot be entered by the primary latch 232, then the only factor which may result in opening the circuit breaker is some structural defect in any of the links.

My circuit breaker operating mechanism, howeve has been designed so that each of the links is formed not merely from a single plate but from a plurality of plates tied together and rigidified by the tie plates so that the structure thereof is able to resist the physical shocks which may be directed against it.

As seen in Figure 3, closing of the circuit breaker is effected by rotating the handle 32% to the position shown in Figure 3 in order to raise the operating link 2%.

The operating link 28% is held in raised position at this time by the fact that the roller 355 carried thereby is engaged with the helical cam on the cylindrical casting 352 which the handle of shaft 359 engages.

As long as the members are in the position shown in Figure 3, then the helical cam 353 sup ports the roller 355 and prevents the operating link from dropping down.

Normally the members shown in Figure 5 (previously described) are designed to rotate the handie to neutral position after the pin 205 on the operating link is engaged by the abutment 225.

When, however, the handle is held in the position shown in Figure 3, then the helical cam 353 abuts against the roller SE5 and thus prevents the operating link 22% from descending, even though the abutment 225 may be swung out of the way.

Accordingly, my lock-in device is designed to maintain the cylindrical casting $52 in the position shown in Figure 3 so that the helical cam will engage the roller 355 when the operating link is raised and thus prevent the operating link from descending even though the abutment 225 may be jarred out of position.

For this purpose a lever 5% (Figures l0, l2, and 19) is provided. This lever is preferably made integral with the squared handle shaft 35% and is provided with a hook 5i i.

The shaft 351! and the lever Eli: are rotatecl clockwise with respect to these figures when the circuit breaker is moved to closed position. At this time the l ver bid is moved to a horizontal position as shown in Figures and 19 where the hook is moved to a position opposite a hook 585 operable by shaft 59 5.

Hook 5% is mounted on a locking plate 5M which is rotatably mounted on the pin 382.

Plate Pitt is bifurcated at 583 and. the tines 58:3 and 535 surround the shaft 5% i.

When the handle is rotated clockwise to close the cir uit breaker, then, in order to utilize the lock-in device to its fullest extent, the handle at the completion of the closing movement is held horizontal so that the lever file is in the horizontal position shown in Figures 12 and 19.

At tl s time, the cylinder 58% is moved axi ally by pressing the handle mounted on the extension 513 inwardly. This results in the looking of the tripping latch in the manner previously described.

After the cylinder too has been moved to complete its axial movement, it is then rotated clockwise in order to efiect the locking thereof in the manner previously described.

This clockwise rotation, of course, rotates the shaft 5M in the same direction. Since shaft 5535' is eccentric with respect to the center of rotation of cylinder 5%, rotation thereof results in a counterclockwise rotation of the locking plate 53! around its pin 382.

Consequently, the hook 586 engages the hook HI and maintains the lever 575 in horizontal position and thus maintains the handle and operating members in the positi n shown in Figure 3 where the helical earn 3555 supports the roller-355 of the operating link and prevents the same from trip ing.

In this way, therefore, even though the abutment 225 should be jarred out of position, there is no effect on the operating arm Edit, since it is supported by the engagement of hook with hook 5,?! which maintains the helical cam in supporting position.

It may be noted that this device makes possible the use of the lockin mechanism to effect a tripping of the circuit breaker since it contains parts which may readily be used to effect such a tripping action as described in connection with Figure ii. The necessity for other manual trip-ping members which may otherwise have been used is dispensed with.

Essentially, however, the lock-in device is designed to maintain the circuit breaker in closed position irrespective of any physical jars, shocks or electrical overload to which the circuit breaker may be subjected.

Since, in this case, the tripping of the circuit breaker depends on the movement of a milled portion of a. shaft into registry with a latch tip, the movement of the shaft to a position all) 16 where an unmilled portion thereof engages the latch tip affects the positive look.

In milled latches of the type herein used, there is only a very small area of the shaft in engagement with a correspondingly small area of the latch which prevents the entry of the latch into the milled portion. This is sufiicient for normal operation.

An extreme physical shock such as may occur in the case of gun fire may, however, wear or break the metal sufiiciently to permit the tripping action to occur. By moving the milled shaft so that an unmilled portion thereof engages the latch tip, then the full structural strength of the entire shaft is utilized to withstand the shock and it becomes physically impossible for a tripping action to occur.

Likewise, since the abutting element 225 is held in position by a spring, a physical shock or jar may conceivably move it to a position where it will be disengaged. A sequence of fortuitous circumstances which may produce this effect may at first seem inconceivable since the abutment is prevented. from rotating counterclockwise with respect to Figure 3 by reason of its engagement with the tie-plate 221 of the latch lever 2H8; and further since its rotation clockwise Would require it to raise the pin 251 i and thus raise the pin 259 to compress the main contacts even further while the opening spring is rendered inefiective by the support given by the latches to the lever 3 3.

But, since the shocks attained by recoil or impact in the case of gun fire are for the most part immeasurable and at times of inconceivable force, even the possibility of the movement of the abutment 225 out of position is provided for by the positive support for the operating link 2% herein set forth.

The lock-in device itself is rendered shockproof by the plurality of movements which are required in order to unlock the circuit breaker. For this operation it is necessary (referring to Figure 12) once more to push the handle carrying extension 5 i3 inward against the compression of spring 5&5, then to rotate the handle carrying extension and the cylinder to a position where the spring may push the cylinder out once more.

While it may be conceivable that the shock of gun fire might cause the cylinder sec to vibrate axially against the pressure of the compression spring 556, it is inconceivable that such a shock would produce the complex action herein required where the unlocking movement requires first an axial movement against the force of the compression spring and then a rotational movement against the torsional resistance of spring 555. Further, the cylinder is held in lock-in position by the interengagement of hooks 5H and 589 on members are and 58!.

Accordingly, the lock-in device of the present invention not only prevents electrical fault conditions and physical forces from tripping the circuit breaker but is itself shock-proof.

In the foregoing, I have set forth my invention and described its operation thereof in connection with preferred embodiments thereof. Many variations vrltl'un th spirit of the di closure should now be obvious to those skilled in the art. Accordingly, I prefer to be bound not by the specific disclosures herein but only by the appended claims.

I claim:

i. In a circuit interrupter having a movable contact structure engageable with a comple-' mentary contact; means biasing said movable contact structure to open position; operating means for moving said movable contact structure into engagement with said complementary contact; means for retaining said movable contact structure in engagement with said complementary contact; a releasing means having a first and "end position, operable to release said last ed retaining means when operated in response to predetermined circuit conditions when in its first position with respect to said retaining means, and inefiective when operuted in response to predetermined circuit conditions to release said retaining means when in its second position with respect to said retaining means; and means for moving said releasing means between said first and second position.

2. In a circuit interrupter having a movable contact structure engageable with a complementary contact; means biasing said movable contact structure to open position; operating means for moving said movable contact structure into engagement with said complementary contact; means for retaining said movable con.- tact structure in engagement with said complementary contact; a releasing means having a first and a second position, operable in response to predetermined circuit conditions to release said last mentioned retaining means when in its first position with respect to said retaining means, and ineifective when operated in response to predetermined circuit conditions to release said retaining means when in its second position with respect to said retaining means; and means for moving said releasing means between said first and second position, said last mentioned means comprising members operable to lock said releasing means in said second position.

3. In a circuit interrupter having a movable contact structure engageable with a complementary contact; means biasing said movable contact structure to open position; operating means for moving said movable contact structure into engagement with said complementary contact; means for retaining said movable contact structure in engagement with said complementary contact; a rotatable releasing member, having a first and a second position, operable to release said last mentioned retaining means and means for rotating the same to effect opening of said circuit breaker; said rotatable releasing member comprising a latching portion registerable With said retaining means in said first position and also comprising means for maintaining said retaining means in operative position, said last mentioned maintaining means being registerable with said retaining means in said second position; and a locking device for moving said releasing member from said first position to said second position.

4. In a circuit interrupter having a movable contact structure engageable with a complementary contact; means biasing said movable contact structure to open position; operating means for moving said movable contact structure into engagement with said complementary contact; means for retaining said movable contact structure in engagement with said complementary contact; a rotatable releasing member, having a first and a second position, operable to release said last mentioned retaining means and means for rotating the same to effect opening of said circult breaker; said rotatable releasing member comprising a milled portion registerable with said retaining means in said first position and also comprising a portion whose cross-section is circular for maintaining said retaining means in operative position, said last mentioned circular portion being registerable with said retaining means in said second position; and a locking device for moving said releasing mem er from said first position to said second position; said releasing member being rotatable in each position thereof; said circular cross section portion on said releasing member when said releasing member is in said second position being in operative engagement with said retaining means irrespective of the angular position of said releasing member; said locking device also engaging said operating means to lock the same in closed contact position.

5. In a circuit interrupter having a movable contact structure engageable with a complementary contact; means biasing said movable contact structure to open position; operating means for moving said movable contact structure into engagement with said complementary contact; means for retaining said movable contact structure in engagement with said complementary contact; releasing means operable to release said last mentioned retaining means; and a locking device engageable with said releasing means to render the same ineffective, said locking device comprising a cylindrical shaft, said shaft being slidable longitudinally between a non-locking position and a locking position; said cylindrical shaft preventing the release of said retaining means when said shaft is moved to a locking position; and additional means associated with said cylindrical shaft for maintaining said shaft in said locking position.

6. In a circuit interrupter having a movable contact structure engageable with a complementary contact; means biasing said movable contact structure to open position; operating means for moving said movable contact structure into engagement with said complementary contact; means for retaining said movable contact structure in engagement with said complementary contact; releasing means operable to release said last mentioned retaining means; and a locking device engageable with said releasing means to render the same inefiective, said locking device comprising a cylindrical shaft, said shaft being slidable longitudinally between a non-locking position and a locking position; spring means engaging said shaft and urging the same to nonlocking position; said cylindrical shaft preventing release of said retaining means when said shaft is moved to a locking position, said shaft being rotatable on its own axis; means for rotating said shaft in a predetermined direction when the same has been moved to a locking position; a groove in said shaft, a stationary member registering with said groove; said groove having a longitudinal course on said shaft; said stationary member registering with one end of said groove in the non-locking position of the shaft and with the opposite end of the groove in the locking position of the shaft; said groove also having a circumferential course communicating with said longitudinal course at said opposite end; said stationary member entering said circumferential course when the shaft is rotated in a predetermined direction after the locking position is reached.

7. In a circuit breaker having a pair of cooperating contacts which engage and disengage, means responsive to circuit conditions for operating said contacts to disengaged position, means for manually engaging said contacts, manually operable means for efiecting disengagement of said contacts, locking mechanism for locking said contacts against disengagement by said first mentioned means, said locking mechanism having a p-luraiity of set positions, an operating member having a plurality of set positions for operating locking mechanism to each of said posisaid operating member being movable axially to operate said locking mechanism to its operative position for loclnng said contacts in engagement, said operating member being also operable to operate said contact disengaging manual means.

In a circuit breaker having a pair of cooperating contacts which engage and disengage, means responsive to circuit conditions for operating said contacts to disengaged position, a locking mechanism having a linear movement to a pluraiity of predetermined positions in one of which it effective for locking said contacts against tripping by said first mentioned means, an operating member having a plurality of set positions for operating locking mechanism to each or" said positions, said operating member being movabie axially to operate said locking mechanism to its operative position and means cont lied by said operating member for looking contacts tripping said first mentioned means.

9. In a circuit breaker having a pair of cooperating contacts which engage and disengage, means responsive to circuit conditions for operating said contacts to disengaged position, means for manually engaging said contacts, manually operable means for eiiecting disengagement of said contacts, locking mechanism for locking said contacts against disengagement by said first mentioned means, said locking mechanism having a plurality of set positions, an operating member having a rotary and axial movement for passing between a plurality of set-positions, the axial movement of said operating member operating said locking mechanism to its positions, for locking said contacts in engagement against disengagement by said first mentioned means, said operating member being rotatable to Operate that said manually operable contact disene sing means.

10. In a circuit breaker having a pair of cooperating contacts which engage and disengage, means responsive to circuit conditions for operating said contacts to disengaged position, looking mechanism for locking said contacts against disengagement by said first mentioned means, said locking mechanism having a plurality of set positions, an operating member having a plurality of set positions for operating said locking mechanism to each of said positions, said operating member being movable axially to operate said locking mechanism to its operative position for locking said contacts against disengagement by said first mentioned means, said operating member being rotatable and locked at said axially moved positions.

11. In a circuit breaker'having a pair of cooperating contacts which engage and disengage, means responsive to circuit conditions for operating said contacts to disengaged position, manually operable means for disengaging said contacts, a locking mechanism having a linear movement to a plurality of predetermined positions in one of which it is effective for locking said contacts against disengagement by said first mentioned means, an operating member having a plurality of set positions for operating said locking mechanism to each of said positions, and means whereby said manual operating, member is ineffective until said locking mechanism has first been rendered ineffective.

12. In a circuit breaker having a pair of cooperating contacts which engage and disengage, means responsive to circuit conditions for operating said contacts to disengaged position, a locking mechanism having a linear movement to a plurality of predetermined positions in one of which it is effective for locking said contacts against disengagement by said first mentioned means, an operating member for operating said locking mechanism to each of its positions, and means controlled by said operating member to disengage said contacts.

13. In a circuit breaker having a pair of cooperating contacts which engage and disengage, means responsive to circuit conditions for operating said contacts to disengaged position, a locking mechanism for locking said contacts against disengagement by said first mentioned means, toggle mechanism controlled by said first mentioned means for controlling the disengagement of said contacts and means controlled by said locking mechanism for locking said toggle against collapse.

14. In a locking mechanism for an electric switch having relatively movable cooperating contacts provided with actuating means for effecting a circuit closing movement thereof together with means for holding the contacts in the circuit closing position; a movable member for effecting the release or said holding means, and

means controlled by said member upon movement thereof to a predetermined position for preventing the release of said holding means;

15; Ina locking mechanism for an electric switch having relatively movable cooperating contacts provided with actuating means for effecting a circuit closing movement thereof together with means for holding the contacts in the circuit closing position, a movable member for effecting. the release of said holding means and means controlled by said member upon movement thereof to a predetermined position for preventing the separation of said contacts.

16. In a locking mechanism for n electric switch having relatively movable cooperating contacts provided with actuating means for effecting a circuit closing movement thereof to gether with means for holding the contacts in the circuit closing position; a movable member for effecting the release of said holding means and means controlled by said member upon movement thereof to a predetermined position for preventing the release of said holding means and to another predetermined position for preventing'the separation of said contacts.

WILLIAM M. SCOTT, JR. 

